SM811

Hi Ladies and Gentlemen,

Simple (or maybe difficult) question I have about HI. Could you tell (explain) me what exactly is doing SM811? (Setup is: PM865(Red), SM811(Red) with SM link, BC810(Red))? What does SM811 supervise? Somehow informations in Safety Manual are not so clear for me or maybe I don't understand.

Thanks a lot for answer

with best regards

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bocian Rank: 2163

Asked 2 years ago

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Besides running application program, SM811 runs plethora of diagnostics, so that in the event any failure is detected, safety system can bring the process to safe state.
One of the example of diagnostics running in SM811 is mentioned in safety manual. Please search for VMT in safety manual.
Another example is "safe peer to peer communication" including CRC checks, Sequence errors, frame corruption etc.

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by bocian Rank: 2163 on 6/22/2016 11:21:08 PM | Like (0) | Report

What I read (please correct me if I understand incorrectly) in SIL2 and lower SM811 works as diagnostic module and only check what and, if correctly, is executing in PM865. In SIL3 SM811 has exactly the same application like PM865 and compares both of them. If anything goes wrong then set all to safety state?

by Vineet Rank: 113 on 6/22/2016 11:30:52 PM | Like (0) | Report

your understanding is right that SIL2 marked applications are run 1oo1D configuration. Application run in PM and diagnostics are implemented in SM

by bocian Rank: 2163 on 6/23/2016 12:37:44 AM | Like (0) | Report

Now another question about. When Failure is detected what does it mean "bring the process to safety state?" If discrepancy was detected, but PM865 works, what then?
How the DO880 will behave or in case of SIL2 what will do AO845 card?

by Vineet Rank: 113 on 6/23/2016 2:23:03 AM | Like (0) | Report

Normally, for safety application, safe state is de-energized. ie 0. which will result in shutdown.
Discrepancy is detected by comparing results of PM and SM, which means PM has to be operational, otherwise you will have shutdown, in any way.
DO880 behaviour is described in safety manual (under heading "DO880 High Integrity Digital Output Module")
AO845 is not SIL certified module.

by bocian Rank: 2163 on 6/23/2016 2:45:46 AM | Like (0) | Report

Exactly. AO845 is not certified but can be used. What then?

by bocian Rank: 2163 on 6/23/2016 2:52:43 AM | Like (0) | Report

and I still do not understand what means shutdown in case of failure. My case is: SM811 or PM865 detected an discrepancy. What happen with PM865? Is it shutdown of PM865? If PM865 is shutdown then does DO880 settings take an action?

by Vineet Rank: 113 on 6/23/2016 3:51:49 AM | Like (1) | Report

if there is discrepancy between PM & SM and it's ESD type of application ie safe state as zero, both PM & SM will be shutdown, thereby de-energizing the output.
AO845 can't be used for safety purpose. which means, you can't it output channels in SIL3 application. In other words, you will have to use NON SIL application in the controller to connect AO845

by bocian Rank: 2163 on 6/23/2016 4:29:39 AM | Like (0) | Report

Thanks for answers. Still is for me interesting what happen with AO845 in SIL2 (can be used) - but is not so important now...

by bocian Rank: 2163 on 6/23/2016 4:39:53 AM | Like (0) | Report

But.. Could you give me a tip how to simulate or produce a discrepancy error( SM != PM)? :)

by Vineet Rank: 113 on 6/23/2016 9:33:51 PM | Like (0) | Report

If you read the safety manual, you can connect non safety critical modules ie AO845 in SIL2 configuration, system will present a warning before download and in SIL3 application, you will get error for such configuration. The loop will be classified as NON SIL only.
Discrepancy between PM and SM is rare phenomenon and can't be simulated.

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Vineet Rank: 113

Answered 2 years ago

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As far as I know, SM run a copy of the SIL application and compare its own calculations with the ordinary processor. SM also supervise hardware.

In case of disagreement or hardware fault, a shutdown is initiated.

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Stefan Stromqvist AKS expert

Rank: 1

Answered 2 years ago

Hi,

The main function of the SM811 is to act as a monitor for the hardware and software execution of PM865. The safety module SM811 is a CEX Module, based on SM810. It provides intelligent supervision of a controller (AC800M) during nonSIL & SIL1-2 and SIL3 application.

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